Modern drug discovery and design programs use computer aided drug discovery (CADD) for identifying and optimizing bioactive compounds used for developing new drugs. It is also known by alternative terms such as in-silico pharmacology and computational therapeutics. CADD approaches are vital in identifying viable drug candidates at a low cost. These approaches are usually divided into two types, namely, structure-based and ligand-based drug design approaches. Both these approaches are used to identify suitable lead molecules. These computational methods are useful for reducing the use of animal models in pharmacological research, assisting in the rational design of novel and safe drug candidates, repositioning marketed drugs, and assisting medicinal chemists and pharmacologists throughout the drug discovery process. This book is a compilation of chapters that discuss the most vital concepts and emerging trends in the usage of computers for drug discovery and design. It will provide comprehensive knowledge to the readers.